The present invention pertains to fluid delivery devices, and, in particular, to a sensing system for determining volumetric flow or other characteristics of the fluid being delivered.
A variety of known types of devices are used to deliver fluid medication to a patient. Such delivery devices can be simple in design, such as a standard syringe that is manually operated to deliver medication through its attached needle, or can be more complicated in design, such as infusion pumps that deliver medication through a cannula.
For many delivery devices, the amount of fluid to be delivered during an intended use is less than the complete medication contents of that device. Especially for such delivery devices, being able to determine or check the amount of fluid actually delivered in a given use may be of high importance.
Many existing devices use a container or cartridge from which medication is forced by advancement of a plunger within the container barrel. Determining how far the plunger has moved, or how far an element driving the plunger has moved, may serve as a proxy for determining the volume of medication that has been delivered from the device. However, such a means of determining the volume may not always prove suitable, such as if the implementation is overly complex, or the plunger is subject to large deformation, or the movement of the driving element does not result in an output that is readily useable by, for example, an electronic dosing system.
Thus, it would be desirable to provide a sensing system, or a delivery device that employs such a sensing system, that can overcome one or more of these and other shortcomings of the prior art.